Verdet constants

If the frequency-dependent perturbation is an electric field then pn) can be used to calculate the frequency-dependent polarizability that must be perturbed to evaluate the imaginary Verdet constant. [Pg.59]

In this section we have described the calculation of u (1) and 1) with TDDFT perturbed by a magnetic field. These quantities, in combination with u/0) and (0) obtained from an unperturbed TDDFT calculation, can be used with Eqs. (11, 17, 30, or 32) as appropriate to evaluate, respectively, Bj, Aj, Cj 1, or C/° 2 and thus an MCD spectrum using Eq. (33). We have explicitly avoided orbitally degenerate ground states and therefore cannot yet calculate classical C terms. This problem will be discussed in Section II.C.4 but before doing so, we will describe the calculation of MCD intensity from the imaginary part of the Verdet constant where the MCD intensity itself is calculated rather than parameters associated with the various MCD terms. [Pg.65]

C.3. A and terms from the imaginary part of the Verdet constant... [Pg.65]

The calculation of MCD intensity from the imaginary Verdet constant includes fewer steps, in part because the current implementation is limited to closed-shell molecules. The process followed is as follows ... [Pg.71]

Calculation of the MCD intensity of a closed-shell molecule through the imaginary Verdet constant produces a result as a function of w but no further breakdown of the intensity. There are advantages to this approach but it does mean that individual and A term parameters are not calculated. An MCD spectrum calculated from Im[V] can yield A and term parameters by fitting the spectrum with suitable band-shape functions in much the same way the parameters can be extracted from an experimental spectrum. [Pg.73]

The term parameters of the lowest two allowed transitions of ethene calculated with different methods and different choices of computational parameters (48,51,98,105) are summarized in Table I. Included in the table are results obtained with four different basis sets. In combination with these basis sets the MCD parameters were obtained in the transition-based approach through solution of Eq. (60) by direct numerical solution (labeled Direct in Table I) and by expansion in a set of transition densities according to Eq. (72) (labeled SOS ). In some cases approximate forms of the A(1) and B(1) matrices were used (labeled Approx, see Eq. (64) and the discussion following it). MCD parameters derived from a fit to a spectrum obtained by calculation of the imaginary part of the Verdet constant are labeled as Im[V]. The parameters obtained from a fit to the spectrum obtained from the approximate form of Im[V] (see Section... [Pg.75]

V is called the Verdet-constant it depends only slightly on the temperature, but varies markedly with the wavelength of the light measurements are normally carried out... [Pg.57]

The molecular magneto-optical rotation D is a function of the refractive index n, the density d, the Verdet constant V and the molecular weight M ... [Pg.59]

Calculations of the fine-structure parameters by Veseth,258 the spin-orbit contribution to the zero-field splitting,259 and the Verdet constant for O2 have also been reported.260... [Pg.114]

Natural optical activity is based on the structure of the molecules (optically active centres). Artificial optical rotation is found in magnetic fields the Faraday-Verdet effect or Magneto-Optic Effect, discovered by Michael Faraday in 1845. The theoretical basis for this effect was developed by James Clerk Maxwell in the 1860s and 1870s. From investigations on small molecules we know that the study of magneto-optical rotation offers interesting correlations with the chemical structure and that additive properties of the Verdet constant have been found. [Pg.299]

This relationship is the Faraday effect. The magnetic field is generated in an air core coil inside of which is a rod made from glass having a high Verdet constant. Now,... [Pg.309]

With respect to a related measurement. Waring and Custer (2139) review the data on Verdet constants. The magneto-optic studies do not reveal distinctive effects of the H bond. Waring and Custer feel the negative results serve as additional magnetochemical evidence that the H bond occurs as simple electrostatic attraction. ... [Pg.65]

Verdet constants have been investigated in [74] and [38] for a few centro-symmetric molecules using coupled-cluster response-theory techniques. For atoms, corresponding results can be found in [149]. [Pg.74]

Verdet constants for Hj, N2, C2H2, and CH4 have been measured at various frequencies (at 1 atm and 298 K) by Ingersoll and Liebenberg [151] in 1956 and are considered to be accurate within 1%. The claimed accuracy has been confirmed in the case of - by the explicitly correlated results of Bishop and Cybulski [150] and again by the FCI/d-aug-cc-pV5Z results of [74] (see Table 10). [Pg.75]

For N2, C2H2, and CH4, Fig. 3 shows the deviation (in percent) from experiment for the calculated Verdet constants. As already discussed, for both Nj and CjIIj triples corrections are substantial, as their inclusion brings the computational results within 1% of the experimental values. However, in the case of N, consideration of vibrational effects (about 1.3%, obtained at the CC,SD/t-aug-cc-pVTZ level using... [Pg.75]

Table 10. FCI Verdet constant. (a.u. x Uf) for If at four different frequencie. ...

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